Employment status passages and psychosocial well-being.

Medical students entering the labor market were studied to find out whether the improvement of psychosocial well-being depends on characteristics of their careers. Psychosocial well-being was described on the basis of psychosomatic stress symptoms, psychological distress (General Health Questionnaire), and strain resistance resources (Sense of Coherence). The 3-year follow-up showed that among women the improvement of strain resistance resources was delayed in the group with several entries into work. Among men the findings suggested associations between stress symptoms and career characteristics. Most of the results, however, did not support the hypothesis about the division of the participants into those with a stable career and improving well-being and those with a fragmented career and low well-being. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Determination of non-polar and mid-polar monomeric oxidation products of stigmasterol during thermo-oxidation

Oxidation products of stigmasterol were characterised by their polarity and molecular size using solid phase extraction (SPE) and high-performance size exclusion chromatography (HPSEC) methods. Monomeric oxides were studied further by GC–MS and GC–FID. The focus was on identifying and quantifying non-polar and mid-polar monomeric oxides after SPE fractionation. Commercial stigmasterol was subjected to 180 °C up to 3 h. Six oxidation products were identified by GC–MS in the non-polar and mid-polar monomeric fractions; all appeared during the first hour of heating. Quantification by GC–FID showed an increase in the non-polar and mid-polar oxidation products during the heating time, and their amounts reached values of 6.1 and 47.0 g/kg of commercial stigmasterol, respectively. Polar oxidation products commonly measured reached a value of 193 g/kg after 1 h of heating, while after 3 h of heating their concentration was only 164 g/kg. Since as much as 550 g/kg of stigmasterol was decomposed, the monomeric products explained only partly the stigmasterol loss. Dimeric and polymeric products contributed to 165 g/kg of the loss showing the importance of polymerisation reactions at 180 °C.     

Oxidative stability of phytosterols in some food applications

The oxidative stability of phytosterols as lipid compounds can be defined as their resistance to oxidation and thus the formation of phytosterol oxidation products. We studied the oxidative stability of phytosterols during processing and long-term storage in phytosterol-enriched milk powder and heat-treated milk, and in microcrystalline phytosterol suspensions in different fats and oils. All of these food applications were observed to be stable despite the heat treatments used in their processing and the long-term storage even at slightly elevated temperatures. The largest change in the phytosterol oxide content was determined for phytosterol-enriched milk powder stored at 38°C for 12 months. During this period the percentage of phytosterol oxidation grew from 0.03 to 0.07%. Based on our observations, we concluded that food applications tested here were unlikely to represent an important source of phytosterol oxides. Furthermore, the formation of phytosterol oxides did not seem to be limiting factor for manufacture and subsequent storage of these products.     

Contents of dietary fibre components and their relation to associated bioactive components in whole grain wheat samples from the HEALTHGRAIN diversity screen

A large and diverse material collection of whole grain wheat samples (n = 129) was analysed for total dietary fibre (TDF) content and composition, including fructan (11.5–15.5%). Correlations between the dietary fibre components, associated bioactive components (e.g. tocols, sterols, phenolic acids and folates) and agronomic properties previously determined on the same samples were found with multivariate analysis (PCA). Samples from the same countries had similar characteristics. The first PC described variation in components concentrated in the starchy endosperm (e.g. starch, β-glucan and fructan) and the dietary fibre components concentrated in the bran (e.g. TDF, arabinoxylan and cellulose). The second PC described the variation in kernel weight and other bran components such as alkylresorcinols, tocols and sterols. Interestingly, there was no correlation among these different groups of bran components, which reflected their concentration in different bran tissues. The results are of importance for plant breeders who wish to develop varieties with health-promoting effects.     

Effects of esterification on the formation and decomposition of steryl hydroperoxides

The aim of the study was to investigate the effects of esterification on the hydroperoxide formation and decomposition of steryl ester to be able to evaluate early phases of autoxidation. In order to study hydroperoxides of intact steryl esters, a novel HPLC–ELSD method was developed. Steryl ester hydroperoxides were separated using a silica column with heptane-MBTE gradient. The method was applied to study the formation and decomposition of steryl moiety hydroperoxides in cholesteryl stearate during heating at 100 °C. To investigate the effect of esterification, also the formation of hydroperoxides in free cholesterol was measured. To confirm the results obtained by HPLC and to follow the decomposition of the hydroperoxides, peroxide values and secondary oxidation products were determined. The new HPLC showed that 7α- and 7β-OOH were the predominant hydroperoxides. In purified cholesteryl stearate, their amounts were highest (47–62 mg/g) after heating for 2–3 days, and after 4 days only small amounts were found. The formation of secondary oxidation products was marked when the amount of hydroperoxides was high. Presence of impurities in the commercial steryl ester preparation increased significantly the oxidation rate. Free cholesterol oxidised more slowly than the ester. The amount of 7-OOH epimers was only 2.6 mg/g for free cholesterol after 3 days. In conclusion, the new method was shown to be a useful tool for the determination of individual intact steryl ester hydroperoxides. The esterification of sterol affected both the rate of oxidation and the amount of formed oxidation products.     

Evaluating the efficiency of integrated systems in the process industry–Case: Steam cracker

A literature survey indicates that decisions about whether to reject or accept an investment are largely based on financial factors. The survey also indicates that a comparison of different efficiency improvement studies is difficult because their results are not readily commensurable. From the management perspective, more information on the physical aspects affecting efficiency is needed. From the engineering perspective, studies on integrated processes deal with a number of criteria that are often in conflict with each other, and for which information is difficult to produce.This paper discusses ways to analyse efficiency improvement studies in integrated industrial processes. The paper demonstrates how these analyses could be made more comprehensive. The paper presents a case study where test runs and simulations were carried out to improve process efficiency by adjusting process operating parameters. The case study was re-evaluated using a novel approach that has been developed to assess the efficiency of integrated systems. This includes considerations from three design perspectives: energy efficiency, material efficiency and operational efficiency, which, when analysed simultaneously, result in a more complete set of design and evaluation criteria.     

Liquid chromatography mass spectrometry for plant sterol oxide determination in complex mixtures

Plant sterol oxidation products were determined by a sensitive liquid chromatography (LC) method with atmospheric pressure chemical ionization mass spectrometry (APCI-MS). Fragmentation of oxides was studied with stepwise fragmentation (full scan, MS², MS³) with ion trap tandem mass spectrometry. The applicability of the method was investigated using thermo-oxidized (180 °C) sterol mixture containing sitosterol, campesterol, stigmasterol and brassicasterol as a model sample. With this method, all major oxidation products of sitosterol, campesterol, stigmasterol and brassicasterol could be detected in the same run without derivatization. This LC-MS method proved to be a powerful alternative to gas chromatographic (GC) methods for the analysis of plant sterol oxides in complex mixtures and is a promising tool for future oxidation mechanism studies.     

Sensory and chemical characterisation of fats used as spreads on bread

Ten dairy fat or margarine-based spreads with 40, 60 or 80% fat, were compared pairwise for their similarity/dissimilarity. The sensory profiles, fatty acid compositions and NaCl contents were also determined. In multidimensional scaling analysis, the three dimensions obtained distinguished between 1) the 80% spreads containing mainly dairy fat vs. others, 2) the spreads containing 40% fat vs. others, and 3) certain individual samples. Polynsaturated vs. saturated fatty acids described dimension I (butter/notbutter), whereas the monounsaturated fatty acids were related to dimensions II and III. The P/S ratios ranged from 0.03 to 2.09. From a sensory viewpoint the major choice offered to the consumers seems to be the one between traditional spreads containing 80% dairy fat and all the remaining spreads.     

Enzymatic hydrolysis of steryl ferulates and steryl glycosides

Steryl ferulates (SF) and steryl glycosides (SG) are phytosterol conjugates found characteristically in cereals. Currently, little is known about their properties with respect to enzymatic hydrolysis. SF and SG were extracted and purified from rye and wheat bran. Their percentages of hydrolysis with different enzymes were studied using normal phase HPLC with UV detection for steryl ferulates and evaporative light scattering detection for steryl glycosides. Steryl ferulates were hydrolysed by mammalian digestive steryl esterases. It was further demonstrated that a mixture of steryl ferulates from rye and wheat was hydrolysed much more effectively than a steryl ferulate mixture from rice (commonly known as γ-oryzanol), suggesting greater bioavailability in non-rice steryl ferulates. Steryl glycosides were hydrolysed by a commercial microbial β-glucosidase preparation (cellobiase), but were not effectively hydrolysed by two other highly purified β-glucosidases. These results demonstrate for the first time the potential use of enzymes as a replacement for acid hydrolysis in analytical procedures for SG and also provide insights about the potential bioavailability of these sterol derivatives in human digestive systems. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Effect of α- and γ-tocopherols on thermal polymerization of purified high-oleic sunflower triacylglycerols

The antipolymerization effects of α- and γ-tocopherols were compared in model systems composed of purified high-oleic sunflower triacylglycerols at 180°C. γ-Tocopherol was much more effective as an antipolymerization inhibitor than α-tocopherol, partly due to lower oxidizability/disappearance. Purified triacylglycerols of sunflower, rapeseed, and high-oleic sunflower oils were less stable than their nonpurified forms containing tocopherols. Results confirmed that tocopherols per se can act as antipolymerization agents in high-oleic oils at frying temperatures. No synergism was observed when α- and γ-tocopherols were present together although larger amounts of residuals were left for both tocols. Results suggested that high-oleic/high-γ-tocopherol oils (such as high-oleic canola and high-oleic soybean oils) may provide better frying oils than high-oleic/high-α-tocopherol oils (such as high-oleic sunflower oil).